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November 09, 2008

All of that for not — eliminating sweet drinks in schools fails to reduce overall consumption

To receive federal funds for school meal programs, schools have been required since 2005 to implement local wellness policies addressing food and beverages available for sale, as part of the national agenda to lower obesity rates. School vending machines are a source of sodas and other sweetened drinks, mostly only available at the high school level, and have become a focus of efforts to reduce the sweet drinks consumed by young people, under the belief they contribute to obesity. But, to date, there's been no data on whether restricting or eliminating sodas from schools actually matters and has any significant effect on the total sweet drinks and other beverages that high schoolers consume.

During the 2004-2005 school year, Maine instituted a Vending and a la Carte Policy project which limited sodas available a la carte and in vending machines and replaced them with low-fat, low-sugar items. Four high schools volunteered to participate and three schools agreed to serve as controls and make no changes for one school year. A total of 581 students, about 16 years old and mainly Caucasian, volunteered to participate and have their diets evaluated via special age-appropriate food frequency questionnaires. Janet E. Whatley Blum, ScD, associate professor with the Department of Exercise, Health and Sport Sciences at the University of Southern Maine in Gorham, and colleagues with Maine Nutrition Network*, examined the changes in the beverages and quantities that students consumed before and one year after the Maine program was instituted. Their results were just published in the November issue of the Journal of Nutrition Education and Behavior.

An earlier paper published in 2005 in Preventing Chronic Disease described the project in detail. Biweekly and then monthly visits to each of the schools were made by a project team member throughout the school year to ensure and monitor the changes. The changes elicited minimal reactions in two of the schools, but the a la carte changes met resistance from faculty, staff and students in the other two schools. Among the complaints were lack of choices and smaller portion sizes for the same prices. Vending machine changes didn’t elicit adverse reactions, except in the faculty rooms. That earlier paper had promised “follow-up data will provide insight into the impact of the nutrition environmental changes on student variables.” No further reports were published, though, until three years later with this new paper.

Professor Blum and colleagues report that the program significantly reduced the sweetened beverages and diet sodas available in the intervention schools — sugar-sweetened sodas made up 44.1% of the beverages available before the program began and sodas were only 3.6% of total beverages available afterwards. Diet sodas, which had made up 1.3% of available beverages before the project, were completely eliminated. Only sports drinks were preserved for athletes due to concern by school administrators over their fluid and electrolyte needs.

The program was a success in nearly eliminating sweet drinks from the schools.

But, it didn't matter. They found: “Despite a decrease in the availability of sugar-sweetened beverages in the intervention schools, intervention boys and girls did not decrease their overall consumption of sugar-sweetened beverages as compared to control boys and girls.” There were small, insignificant shifts in the beverage consumption patterns, but the authors found that taken together changing the beverage availabilities at school had limited impact on the student’s overall consumption (home, after school, weekends, etc.). This study did not evaluate any of the children’s weights to evaluate the core goal of reducing obesity rates, but it would be a moot point given these null results.

While this was a small study and only ran one school year, it failed to support the effectiveness of school beverage policies in changing student’s overall drink consumptions.

The authors concluded:

The present findings offer support of the feasibility of implementing school food policies that reduce the availability of school SSB. Although reduced availability of school SSB did not influence overall SSB consumption in this convenience sample of Maine high school youth, the efficacy of such school food policies in youth susceptible to obesity is needed.

This study has not been widely publicized by the media, just as we heard little about the intensive two-year study published earlier this year that was to provide evidence for the effectiveness of the School Nutrition Policy Initiative in reducing childhood obesity. This comprehensive program included every initiative popularly believed to reduce obesity and all of the interventions were in accordance with the CDC’s “Guidelines to Promote Lifelong Healthy Eating and Physical Activity” that are being incorporated into school wellness policies across the country. The program was a total failure. Not only had the children’s “healthy eating” behaviors slightly dropped, but it had no effect on the incidence, prevalence or remission of obesity, and resulted in no differences in the children’s heights and weights compared to controls. Most importantly, it failed to evaluate the potential harmful consequences of the intense interventions.

Programs that feel intuitively correct and good aren’t necessarily so when they work from unsupportable premises as to the causes of obesity and chronic diseases. Given the massive resources, and increasingly intrusive interventions for students and families as school and government officials attempt to monitor and control what young people eat in schools, parents and tax paying consumers might begin insisting on some evidence before continuing to support these programs.

* The Maine Nutrition Network (MNN) administers and evaluates the wellness initiatives in Maine’s public schools in accordance with Shaping Youth Behavior (SAY, reviewed here). It’s funded through the Department of Health and Human Services Maine Center for Disease Control and Prevention and the University of Southern Maine’s Muskie School of Public Health.